Deliberate mistake: When James is shot on the courthouse steps, the crowd of reporters that has gathered quickly scatters to escape the gunfire. One of them is a woman in a black windbreaker holding a camera. The camera cuts away briefly and then back to the crowd - you see the exact same people, including the woman in black running in the exact opposite direction as before. The footage was apparently mirrored and repeated for the second shot of the fleeing crowd.
Wrestling with Demons - S3-E12
Deliberate mistake: When Piper froze the demons (near the wrestling) one of the demons moved when she froze him.
Deliberate mistake: When the investigators are in the basement wine cellar, they turn on their flashlights to illuminate the pitch black area as they walk around. However there is a light source moving with the camera shining on them as they are casting a shadow behind them.
Deliberate mistake: Nina first wrote 'Born to Try', the song which was being released by Delta Goodrem (the actress that plays her), along with the show. She then managed to just 'inprovise' the tune and words to her (Delta's) third single 'Innocent Eyes'. I'm sure now Nina is a popstar there will be many more to come.
Deliberate mistake: When a patient who is given CPR is seen in the shot, the person giving the CPR does so with bent arms (the correct way to do it is with straight arms). This is deliberate, as straight-arm CPR puts in an amount of strength that frequently breaks ribs. Many films do CPR with bent arms rather than straight to avoid harming the actor.
Deliberate mistake: Beth shoots Bryce three times in the chest, and he falls face down on the floor. She then drags his body across the floor, also face down, to in front of the sliding door, but there is no sign of blood anywhere.
Suggested correction: In the early Seventies, no television show used blood effects. They were too expensive and would severely restrict potential audiences as television channels were notoriously conservative in those days. This is a creative and technical decision, not a mistake.
Deliberate mistake: On several occasions throughout both series/seasons, whenever a Terminator fires a weapon, they blink. This should not happen because that would be a human reaction - Terminators aren't human. They're made to look and act human, but SkyNet don't focus on the little things; such as emotions, breathing and reflexes. The three most notable instances of this are in Season 1, Episode 5: "Queen's Gambit", Season 2, Episode 21: "Adam Raised a Cain" and Season 2, Episode 22: "Born to Run". In "Queen's Gambit", Cameron blinks as she fires a machine gun at the T-888 in the back of the black van as he runs towards her, in "Adam Raised a Cain" the water delivery Terminator blinks as he shoots Savannah Weaver's nanny Debbie and as he shoots the security guard and Catherine Weaver in "Born to Run".
Deliberate mistake: As the Wraith "stun bomb" activates at the SGC and everyone falls to the ground, it is visible how everyone uses their arms to dampen the fall.
Deliberate mistake: 9/6/10: When Lucas and Jade are getting into the car, look at the road sign behind them. Lucas is driving down a one way street the wrong way. Also the camera light is reflected in the side of the car.
Crisis on Earth-X, Part 2 - S6-E8
Deliberate mistake: During the big battle, Arrow is knocked down and when he opens his eyes, the reflection in his eyes is tilted over to give the sense he's seeing things sideways. But the reflection should still have shown the proper orientation no matter what orientation his eye was at. Think of looking into a mirror and then rotating the mirror to the side, the reflection wouldn't rotate.
Perennials - S8-E11
Deliberate mistake: In the outside shot of the unsub's motel in Pensacola, Florida, the sky is black as if someone behind the scenes tried to digitally remove part of the background in post, but did a really bad job.
Deliberate mistake: In Episode 7, "Bad Moon Rising": When Cash meets Sasha at The Haven, she mentions "Eddie and his bodyguards being blown away". But Eddie was not "blown away", he was neatly decapitated, and in addition, none of his bodyguards were killed. Julian specifically said that he would let them live to elect a new leader. Sasha was present, and would know this.
Edward Mordrake: Part 1 - S4-E3
Deliberate mistake: After Elsa kicks Bette and Dot off the stage, Elsa looks at the sheet of music on the stand and you see the name of the song 'Criminal' and it also states it's by Fiona Apple which is true, but this season is set in 1952, and Criminal wasn't released until 1996.
Deliberate mistake: The layout of the Walsh house, both interior and exterior, is different in the pilot than it is in the rest of the series.
Deliberate mistake: The police car Steve & Danny are driving on the bridge as they approach the freighter has 467 on the roof, which then becomes flipped & backwards a few shots later as they take a sharp right, only to become 467 again (as Danny has conversation with Rachel). (00:38:10 - 00:39:05)
Deliberate mistake: When Ryan and Esposito give Beckett the surveillance tape of Sophie and Uncle Teddy, Beckett's computer reads the disc and plays the tape incredibly fast. Faster than any desktop PC I've ever seen.
In Which We Meet Mr. Jones - S1-E7
Deliberate mistake: Dunham comments that she works for Homeland Security. While the FBI is under the jurisdiction of the Justice Department, she works as part of a special Homeland Security task force; so saying she works for DHS is an accurate statement.
Deliberate mistake: In the episode "Bunk," a man goes in the house looking for his cat. When the cat releases the fumes, it jumps down, but when the man dies, the cat is nowhere to be found. The cat is not mentioned ever again in the episode either.
Deliberate mistake: Season 2, episode 10: After Matt is supposed to be dead underwater, you can see air bubbles coming out from his nose in a close-up, and in a far away shot his head is above the water so the actor can breathe.
Episode #4.3 - S4-E3
Deliberate mistake: Before the gas explodes in the sewer, you can see the base of the Davy lamp glow red. Except that in real life this doesn't happen; the flame simply turns blue and grows taller in the presence of gas. This was probably done to make the scene more dramatic, though.